This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Glycosphingolipid Enriched Microdomains in Cancer Cell Invasion The ultimate goal of this study was to investigate biological processes involving Glycosphingolipid Enriched Microdomains (GEM) and their implication in diseases, such as cancer. Cancer cell invasion is a highly complex and multistep process, that is characterized by altered expression levels of cell adhesion molecules and secretion of proteolytic enzymes, along with changes in expression or activities of a variety of cellular proteins in multiple branching signaling pathways. In addition, the plasma membrane contains membrane microdomains enriched in tumor-associated glycosphingolipid (GSL)-antigens that function as mediators of cell adhesion, and in signaling molecules, providing important locations for cell signaling. Recent studies showed that tumor cell invasion often results from aberrant signaling mechanisms initiated by differential organization and clustering of GSLs and/or membrane proteins, and their assembly with signaling molecules. The synthetic ether lipid analog ET-18-OMe (1-O-octadecyl-2-O-methyl-glycero-3-phosphocholine) was previously shown to influence invasion of human breast and colon cancer cells and is used as a molecular probe to induce cellular invasion in order to explore changes in composition, translocation and organization of crucial molecules and the possible involvement of membrane microdomains. Our results show that reorganization, clustering and assembly of specific membrane proteins and signal transducers with glycosphingolipids in membrane microdomains are responsible for loss of cell-cell adhesion and subsequent result in increased invasiveness of MCF-7 breast cancer cells. In contrast, the invasive behavior of HCT-8 colon cancer cells was initiated through clustering of integrin alpha1 subunits and the activation of associated FAK/cSrc complexes.